SRI international provides a continuing resource for conducting the following types of studies with agents selected for preclinical development through the programs listed above: (1) development of sensitive analytical methods to quantify compounds in plasma, urine, tissues, and other biological matrices; (2) plasma stability and protein binding studies, which are conducted at an early stage of compound development to ensure proper sample handling and to aid in the interpretation of in vivo studies; (3) pharmacokinetic evaluation of test compounds following administration to animals by various routes and schedules, including a determination of bioavailability by various routes; (4) quantification and identification of drug metabolites generated in vivo and in various in vitro systems (S9 fractions, microsomes, hepatocytes, P450 isoforms, liver slices); and (5) correlation of compound effects on putative molecular targets (pharmacodynamic effects) with compound exposures.